Video conferencing (or video teleconferencing) systems have been developed to permit users in two or more separate locations to conduct face-to-face discussions. Through the inclusion of video images of the participants, video conferencing can significantly enhance the effectiveness of a communication session. For example, non-verbal communication also can be exchanged and physical objects can be presented. Accordingly, video conferencing systems have been adapted to a variety of purposes, including distance learning, telemedicine, and remote collaboration.
Early video conferencing systems required dedicated communication circuits to enable the real-time transmission of video data at a rate sufficient to provide an acceptable picture quality. Further, special purpose coder/decoder (codec) systems were employed to perform the audio and video processing, and multiple monitors often were included to support multi-point conferences. Thus, early video conferencing systems were implemented as dedicated systems and were installed in fixed locations. More recently, improvements in communication networks have enabled the development of video conferencing systems using general purpose computing platforms. Improved video compression algorithms also have been developed to reduce the bandwidth requirements for video conferencing applications.
A number of factors can influence the perceived quality of a video conferencing system. For example, if the frame rate is too low, the video presentation at the receiving device can include a strobe effect. Further, for some orientations of the camera relative to the subject, the received image can include noticeable distortion. Either or both of the angle of view at which an image is captured and the angle of view at which an image is presented can affect the level of perspective distortion. Perspective distortion can result from an image being captured at a focal length that is outside of the normal range and is perceived as a visible warping of an object or objects in the captured image. Through perspective distortion, an object or a portion thereof may appear larger than normal with respect to other objects or object portions. Perspective distortion can become more noticeable as the angle of view increases and the distance between the camera and the object decreases.